Ignition amplifying apparatus



Oct. 22, 1968 A. w. EVANS ET AL 3,406,667

IGNITION AMPLIFYING APPARATUS Filed Sept. 29, 1966 2 Sheets-Sheet 2 46b 54b 3; 120 50b INVENTORS ALV/IV W EVANS RUD/ Bf/C/IEL KARL MOKGHEN ATTOHVEVS United States Patent 3,406,667 IGNITION AMPLIFYING APPARATUS Alvin W. Evans, 4501 Winding Way, Sacramento, Calif. 95841; Rudi Beichel, 3244 Shasta Way, Sacramento, Calif. 95821; and Karl Morghen, 19 9th St., Minden,

Nev. 89423 Filed Sept. 29, 1966, Ser. No. 582,824

' 8 Claims. (Cl. 12332) ABSTRACT OF THE DISCLOSURE A stratified charge ignition system for a spark type internal combustion engine. The apparatus comprises; a precombustion chamber coupled in fluid communication with each primary combustion chamber of the engine in place of the spark plug normally coupled thereto; carburetion means to supply a relatively rich fuel-air mixture to each precombustion chamber; and, spark ignition means to effect the ignition of the fuel air mixture supplied to each of said chambers in timed sequence to the operation of the engine. Fluid communication between each precombustion chamber and the primary combustion chamber coupled thereto is provided by an orifice comprising a Borda mouthpiece opening into the precombustion to define an imperforate lip extending thereinto; and a nozzle of substantially truncated conical shape extending from the mouthpiece in diverging relationship relative thereto and opening into the primary combustion chamber.

The present invention relates to an improved ignition device for internal combustion engines and, more particularly, is directed to a smog control system adapted for use on Otto cycle engines. The invention is especially concerned with such a system'facilitating the combustion of an air-fuel mixture having an excess proportion of air in the primary combustion chamber of an internal combustion engine.

Conventional Otto cycle gasoline engines using spark igniters achieve best ignition with air-fuel mixtures containing fifteen to twenty percent excess fuel. Such conditions are required for reliable operation. Leaner mixtures are difficult to reliably ignite, while richer mixtures decrease flame propagation velocity.

Engines employing excess fuel mixtures, however, have the disadvantage that the exhaust gases emitted therefrom contain combustible products. These products are comprised, primarily, of incompletely combusted hydrocarbons. This effect is increased during acceleration, deceleration and all part-load conditions. Under cold starting conditions, choke devices further aggravate this effect by increasing the excess of fuel in the fuel mixtures supplied to such engines. The incompletely combusted hydrocarbons, together with the hydrocarbon fumes discharged from their crank cases, are transformed through a photochemical process into what is commonly called smog.

A reduction of the fuel content of the air-fuel mixture would eliminate the combustible products contained in the exhaust gases emitted from Otto cycle engines, but ignition and combustion propagation in the engines would then become slow and irregular. Under such conditions, the combustion would reach completion late in the expansion stroke. This would lead to hot exhaust gas and 3,406,667 Patented Oct. 22, 1968 the overheating of the engine because of lowering ofthe effective expansion ratio. Engine starting would also become more difiicult, especially in cold weather, due to the further leaning of the air-fuel mixture through condensation of fuel in the intake manifold. For there reasons, conventional carburetors are adjusted to a fuel excess condition that'produces the highest power output. As a the higher turbulence associated with higher speeds, propagation velocity at top dead center is on the order of one hundred feet per second. This applies only for air to fuel ratios between 12.5 and 13.5. Because of the lower energy content of a lean mixture, propagation velocity is reduced to twenty feet per second for an air to fuel ratio of twenty. Lowering of the propagation velocity also occurs at fuel-rich mixtures because of reduced energy of reaction. For example, at an air to fuel ratio of 7, the propagation velocity is reduced to below twenty feet per second.

It has been recognized that a rich air-fuel mixture close to the spark plug and a lean fuel mixture in the remainder of the combustion chamber would improve the utilization of fuel and the thermochemical efliciency of Otto cycle engines. This stratified charge principle currently requires the use of a fuel injection system and is usually combined with intake swirl to produce Stratification by centrifugal effect. With this principle, however, control and balance for uniform complete combustion has not been achieved over a normal operating range of conditions.

Prior art efforts to obtain a stratified charge in Otto cycle internal combustion engines have also suggested the employment of a small secondary chamber around the electrodes of the spark plug to contain a fuel-rich mixture for spark ignition. In such arrangements, an orifice establishes fluid communication between the primary combustion chamber and the secondary chamber and a fuel-lean mixture is supplied to the primary chamber while a fuel-rich mixture if supplied to the secondary chamber. Thus, in operation, the rich fuel mixture is readily ignited in the secondary chamber and a jet of hot gas is discharged through the orifice into the primary chamber. This jet was intended to thoroughly ignite the lean fuel mixture in the primary chamber.

Although the desirability of arrangements of the latter type has long been recognized, these arrangements have not proved successful in actual application. This is believed to have resulted because the inventors and developers of these arrangements did not appreciate the characteristics of flow required between the primary and secondary chambers for successful operation. In any event, even if these characteristics were appreciated, it does not appear that they 'were successfully provided in the prior 3. chambers wherein flow conditions are established between the chambers for optimum engine operation.

Another object of the invention is to provide an arrangement of construction whereby a conventional Otto cycle engine may be converted to a stratified charge engine without major modifications of the engine structure. With respect to this object, it is another object of theinvention to provide an ignition device for ready attachment to an engine to effect the conversion thereof to a Stratified charge system.

Yet another object of the invention is toprovide an ignition system for internal combustion engines wherein all unburned pockets of. combustible fuel are burned to completion during the early phases of the power stroke and, thus, the necessity for anti-knock compounds is avoided. With respect to this object, it is another object of. the invention to eliminate the poisonous exhaust products which result from the employment of lead-containing anti-knock compounds in the fuel for internal combustion engines.

Still another object of the invention is to provide an ignition system for an internal combustion engine that can be adjusted to assure free oxygen content in the combustion products of the engine over its entire operating range. Another and related object of the invention is to provide an engine wherein the exhausted combustion products may be employed to burn off the hydrocarbon fumes emitted from the engine crank case.

A further object of the invention is to provide an ignition system for an internal combustion engine which permits the use of an oxygen-rich lair-fuel mixture for the primary combustion chamber and, thus, eliminates excess carbon residuals.

Still a further object of the invention is to provide an internal combustion engine with an ignition system which, as compared to a conventional ignition system, results in complete combustion over a shorter period of time and the expansion of combustion products over a larger pressure ratio durring the power stroke. With respectto this object, it is another and related object to provide an ignition system for an internal combustion engine adapted to improve its thermal efiiciency and lower the temperature of exhaust gas emitted therefrom. I

In its broadest aspects, the present invention comprises a stratified charge ignition device and system which incorporates a secondary ignition chamber adapted to be coupled in fluid communication with the primary combustion chamber of an internal combustion engine through an orifice and control means operatively associated with said orifice to, upon operation with an engine:

(1) Effectively restrict the flow area of the orifice upon the ignition of an air-fuel mixture in the secondary chamber and establish a pressure differential between the primary and secondary chambers responsive to the ignition to support the supersonic discharge of gas through the orifice and into the primary chamber; and,

(2) Eifectively'open the area of the orifice upon the occurrence of a fluid pressure condition in the primary chamber exceeding that in the secondary chamber and permit the immediate and substantial dilution of gas in the secondary chamber by gas from the primary chamber responsive to the occurrence of such a condition.

As a result of this control means, upon ignition in the secondary chamber, a supersonic jet of hot gas is discharged into the primary chamber to effect complete combustion of the gas therein. Furthermore, during the compression and exhaust strokes of the primary chamber and the portion of the power stroke of the primary chamber after complete combustion therein, gas in the secondary chamber is readily diluted by that in the primary chamber. The latter characteristics have the advantage that gases from the primary chamber produce dilution and scavenging functions, respectively, upon compression and exhaust and backflow and reignition functions immediately after complete combustion during the power stroke.

The foregoing and otherobjects and the details of the invention willbecome more apparent when viewed in light of the following description and accompanying drawings wherein:

FIG. 1 is a perspective view illustrating an Otto-cycle engine of conventional character having the smog control system of the present invention applied thereto;

FIG. 2 is a sectional view illustrating one embodiment of the ignition device of the invention; 7

FIG. 3 is a sectional view illustrating a second embodiment of the ignition device of the invention; and,

FIGS. 4 to 7 are sectional views illustrating, sequentially, the operation of a third embodiment of the ignition device of the invention during the cycle of an Otto-cycle engine.

Referring now to FIG. 1,.the exemplary engine therein is designated in its entirety by the numeral 10. 'This engine is of the conventional six-cylinder overhead valve type and comprises, in part: a-block 12; crank case 14; pan 16; head 18; exhaust manifold 19; fuel pump 20; primary carburetor 22; primaryfuel line 24 leading from the fuel pump 20 to the carburetor 22; distributor 26; six spark plug receiving openings (not illustrated); and, ignition wires 28 leading from the distributor 26 to close proximity with the spark plug openings.

The basic smog control system illustrated in FIG. 1 comprises six ignition devices 30 threadably received, respectively, in the spark plug openings of the engine 10; a secondary carburetor 32; a fuel line 34 leading fromthe pump 20 to the carburetor 32; an intake manifold 36 leading from the carburetor 32 to close proximity with each of the devices 30; and, a plurality of fluid conduits leading, respectively, from the manifold 36 to each of the devices 30. The foregoing basic elements of the system are mounted on the engine in conventional manner by brackets and the like. In the illustrated embodiment, the smog control system also includes a link 40 coupling the primary carburetor 22 and secondary carburetor 32 for simultaneous operation and a breather pipe 42 connnected in fluid communication between the breather of the crank case 14 and the exhaust manifold 19. The breather pipe 42 is connected to the manifold 19 at a point rwherein, during engine operation, the temperature of gas exhausted into the manifold exceeds the ignition temperature of hydrocarbon fumes in the engine crank case. The pipe 42 also has interposed therein a check valve 44 to prevent backfiow therethrou gh from the exhaust conduit to the crank case.

The operation of the primary carburetion and electrical systems for the engine in FIG. 1 is conventional, with the exception that the primary carburetor 22 supplies an extraordinarily lean air-fuel mixture to the primary combustion chambers of the engine. This lean mixture is provided, for reasons which will become more apparent subsequently, to assure that the air content of the air-fuel mixture supplied to the primary combustion chambers will be in excess of that required to burn all of the fuel. The

preferred air-fuel ratio of this mixture is approximately 16:1 to 20:1 and may be provided simply by reducing the area of the carburetor jets in the primary carburetor 22 by about twenty percent.

The secondary carburetor 32 and the intake manifold and fluid conduits cooperating therewith operate through pressure differentials created between the devices 30 and the atmosphere. The operation of the devices 30 will be developed in detail subsquently. Preferably, the secondary carburetor 32 provides an air-fuel ratio offrom 4:1 to 6:1. In the preferred embodiment, the link 40 couples the carburetors 22 and 32 so that the volume of the fuel-air mixture supplied through the carburetor 32 is substantially directly proportional to that supplied through the carburetor 22 through the normal operating range of the engine.

Referring now to FIG. 2, therein is illustrated one of the devices 30 with a spark plug 46 (illustrated in phantom) engaged therein. The device 30 is comprised, primarily, of a housing 48 having therein: a secondary combustion chamber 50; an orifice 52 leading from the chamber 50 to the exterior of the housing; and, a conduit 54 leading into the chamber and comprised, in part, of a valve chamber 56. The chamber 50 has formed in the upper portion thereof a threaded opening 58 adapted to receive the spark plug 46. The conduit 54, similarly, has formed in the upper portion thereof a threaded opening 60 adapted to receive one of the conduits 38. The valve chamber 56 has received therein a pressure differential operated valve 61 of relatively conventional nature. This valve comprises: a seat element 62 threaded into the chamber 56; a valve element 64 slidably received in the seat element 62 for sealed seating engagement therewith upon the occurrence of a pressure condition in the chamber 50 exceeding that in the conduit 54 and for opening upon a pressure condition in the conduit 54 exceeding that in the chamber 50; a stop element 66 received on the valve element 64; and, a compression coil spring 68 interposed between the elements 62 and 66.

The orifice 52 is comprised of a nozzle section of generally truncated conical shape diverging from the chamber 50 to the exterior of the housing. As a result of this nozzle configuration, the gas jet which is discharged through the orifice 52 upon ignition of an air-fuel mixture in the chamber 50 is dispersed to a degree sufiicient to avoid burning of the piston head within the primary cylinder cooperating with the device 30. Control of the degree of dispersion effected in the orfice to satisfy the requirements of a particular engine may be accomplished by varying the length and degree of divergence of the nozzle section.

The elongated nozzle section of the orifice 52 extends longitudinally through an externally threaded section 70 provided on the lower portion of the housing 48. This threaded section is designed for threaded engagement with the spark plug opening of a conventional engine, such as the engine 10, so as to establish sealed communication through the orifice 52 between the primary combustion chamber of the engine and the secondary combustion chamber 50 of the device 30. It is here noted that the elongated character of the orifice nozzle section and the mass of the housing therearound also facilitates the dissipation of heat away from the orifice.

. The orifice 52 opens into the secondary chamber 50 through a mouthpiece 72 of Borda configuration. Although this mouthpiece is rounded slightly from true Borda configuration for heat dissipation purposes, it operaes, essentially, in true Borda fashion. Specifically, the mouthpiece functions to restrict the effective flow area of the orifice 52 upon the outflow of gas therethrough from the secondary chamber 50 and to open the effective area of the orifice upon the inflow of gas therethrough into the secondary chamber. This change of effective area is aerodynamically generated and, where full Borda effect is accomplished, amounts to a change of two to one. From the subsequent description of the operation of the device 30 when attached to the primary combustion chamber of an internal combustion engine, it will be appreciated that this change in effective area causes a relatively low pressure differential during inflow into the secondary chamber from the primary chamber of the engine and a relatively high pressure differential during outflow from the secondary chamber into the primary chamber after ignition of an air-fuel mixture in the secondary chamber.

Referring now to FIG. 3, therein is illustrated an alternative embodiment of the device 30, designated in its entirety by the numeral 30a. The device 30a differs from the device 30, in its basic aspects, primarily in that it incorporates, a self-contained spark plug unit. Thus, with the device 30a, it is not necessary to employ a spark plug, such as the plug 46 illustrated in FIG. 2.

The primary working elements of the device 30a correspond to those of the device 30 in function and, ac-

cordingly, for the sake of simplicity will be designated by numbers differing from those used for the elements of the device 30 only by the subscript a. These elements are as follows: housing 48a; secondary chamber 50a;' orifice 52a; conduit 54a; valve chamber 56a; valve 61a; threaded section 70a; and, mouthpiece 72a. In addition to these elements, the device 30:: comprises the following elements which make up the self-contained spark unit thereof: an annular insulator 74 received around the conduit 54a and having extending radially therefrom a collar 76; gaskets 78 and 80 received around the insulator 74 above and below, respectively, the collar 76; a gasket 82 received around the conduit 54a between the valve chamber portion thereof and the insulator 74; a pair of nuts 84 and 86 threadably received on the upper end of the conduit 54a above the insulator 74; a lead connector 88 lockingly received between the nuts 84 and 86; a central electrode 90 fixed in electrical contact with the conduit 54a and depending downwardly therefrom into the chamber 50a; and, a ground electrode 92 fixed in electrical contact with the housing 48a and extending therefrom into the chamber 50a beneath the electrode 90. The device 30a also includes a sleeve 96 engaged over the gasket 78 and threadably received on the housing 48a to maintain the insulator 74 in sealed, locked engagement with the housing. The conduit 54a is provided with an outwardly extending threaded section 98 to which a fluid conduit, corresponding to the conduit 38, may be connected.

The device 30a is received in the spark plug opening of an engine through engagement of the threaded section 70a with the threads of the opening. After the device is so received, its installation in a system as shown in FIG. 1 is completed by connecting one of the ignition wires 28 to the lead connector 88 and one of the conduits 38 to the threaded section 98.

After installation on an engine, the devices 30 and 30d operate in an identical manner. During this operation, an air-fuel mixture is introduced into the secondary cornbustion chamber of each device on the intake stroke of the combustion chamber of the engine communicating therewith. This function is permitted by the opening of the pressure differential operated'valves 61 and 61a responsive to each such stroke. These valves also function to close the secondary chambers to flow from the carburetor 32 when the primary combustion chamberscommunicating therewith are operating through their power, exhaust, and compression strokes. It is here noted that the walls of the conduit 54a function as an electrical conductor for the central electrode 90 and that the flow of air-fuel mixture through the conduit 54a functions to cool these walls and the valve 61a.

The embodiment of the inventive ignition device illustrated in FIGS. 4 to 7 is designated in its entirety by the numeral 30b. This embodiment differs from those illustrated in FIGS. 2 and 3 primarily in that it is fabricated as an integral part of the engine head cooperating therewith and that the intake valve, designated by the numeral 100, for the secondary combustion chamber therein is operated by a timed mechanical operator (not illustrated) such as a solenoid or cam shaft. This operator is timed so that the valve 100 is open only upon the intake stroke of the primary combustion chamber communicating with the secondary combustion chamber of the device 30b. Thus, the valve 100 performs an operational function corresponding identically to that of the valves 61 and 61a.

For the sake 'of illustration, the embodiment of the ignition device 30b in FIGS. 4 to 7 has been shown employed with an L'head engine, rather than a valve-in-head engine as shown in FIG. 1. This difference does not affect the operation of the device and, accordingly, all comments made herein relating to the operation of the invention on the engine shown in FIGS. 4 to 7 are considered applicable to the engine and system shown in FIG. 1, and vice versa.

The L-head engine shown in FIGS. 4 to 7 is of conventional nature and comprises, in part: a block 102 defining therein a cylinder 104, intake manifold 106 and exhaust manifold 108; a head 110 received on the block to define therewith a primary combustion chamber 112; a piston 114 reciprocally received in the cylinder 104; an intake valve 116 operatively associated with the manifold 106 and an exhaust valve 118 operatively associated with the manifold 108.

The device 30b is comprised of elements, in large part, which correspond operationally to the elements of the aforedescribed device 30. Accordingly, for the sake of simplicity, these elements of the device 30b are designated by numerals corresponding to those of the device 30, followed by the subscript b, as follows: housing 48b;

secondary combustion chamber 50b; orifice 52b; conduit 54b; threaded opening 58b; and mouthpiece 72b. The conduit 54b receives therein through means of a valve guide 120 the aforedescribed intake valve 100. The threaded opening 54b receives therein a conventional spark plug 46b corresponding to the plug 46 of the FIG. 2 embodiment. Although not illustrated, it is to be understood that the engine shown in FIGS. 4 to 7 would include carburetion and ignition components corresponding to those of the engine in FIG. 1 and that a fluid conduit, corresponding to the conduit 38, would be connected in fluid communication with the conduit 54b. The spark plug 46b would also have connected thereto an electrical ignition wire corresponding to the wire 28 and, preferably, the engine would be provided with a breather pipe and valve arrangement similar to the conduit 42 and valve 44.

The operation of the inventive device system will now be described with reference to the embodiment thereof illustrated in FIGS. 4 to 7. It is to be understood, however, that this operation is substantially identical for all embodiments of the invention.

During the intake stroke of the engine, as illustrated in FIG. 4, the pressure within the secondary combustion chamber 50b is reduced and the valve 100 is opened to admit a charge of rich air-fuel mixture to the chamber. This air-fuel mixture is provided by a carburetor corresponding to the carburetor 32 and, preferably, has a ratio of from 4:1 to 7: 1. Some of this fuel-rich mixture, as is designated by the numeral 122 in FIG. 1, is drawn through the orifice 52b and into the primary combustion chamber 112. During this same intake stroke, the primary combustion chamber 112 is also filled with a lean air-fuel mixture through the intake manifold 106. This mixture is provided by a carburetor corresponding to the aforedescribed carburetor 22 and, preferably, has a ratio of 16:1 to 20:1.

Upon the compression stroke, as illustrated in FIG. 5, a portion of the lean air-fuel mixture in the primary combustion chamber 112 is forced through the orifice 52b and into the secondary combustion chamber 50b to effect the dilution of the rich air-fuel mixture therein. This dilutionsfunction is highly responsive and very immediate due to the unrestricted flow area of the orifice provided by the action of the mouthpiece 72b. At the end of the compressionstroke, the dilution thus effected preferably increases the air-fuel ratio of the mixture in the secondary combustion chamber 50b to from 12.5 :1 to 14:1. This range of ratios is ideally suited for ready spark ignition. It is here noted that, during the aforedescribed compression stroke, the valve 100 is maintained closed and, thus, backfiow through the conduit 54b is prevented.

Upon commencement of the power stroke, as illustrated in FIG. 6, the valve 100 remains closed and the spark plug 46b effects ignition of the air-fuel mixture within the secondary chamber 50b. On the latter occurrence, the effective flow area of the orifice 52b is aerodynamically restricted by the mouthpiece 72b and a high pressure differential is established across the orifice. The aerodynamic restriction of the orifice is sufiicient so that gas discharged therethrough from the secondary combustion chamber 50b assumes the form of a jet having supersonic velocity. This jet, upon entrance into the primary combustion chamber, creates great turbulence and ignites the lean mixture therein with an effective propagation velocity of several hundred feet per second. This high propogation velocity is also effected, in part, by a shock wave which travels through the orifice 72b and into the primary combustion chamber immediately prior to the jet. The effectiveness of the jet in igniting gas within the primary combustion chamber is also enhanced by the relatively long jet duration provided by the restriction aerodynamically generated by the mouthpiece 72b.

As a result of the rapid propagation velocity provided 'by the ignition device, complete combustion within the primary chamber is effected at a crank angle of between 5 and 15 after top dead center. Immediately after combustion in the primary chamber 112 is thus completed, and during the remainder of the power stroke, the pressure condition within the primary chamber exceeds that within the secondary chamber 50b. At this point, due to the unrestricted area of the orifice 52b provided by the mouthpiece 72b, backflow of hot gas into the secondary chamber from the primary chamber immediately occurs. Thus hot, air-rich gas is injected into the secondary chamber and any remaining combustible hydrocarbons therein are consumed. The latter characteristic is particularly advantageous, since it functions to clean the secondary combustion chamber and the spark plug.

During the exhaust stroke, as illustrated in FIG. 7, the engine operates in relatively conventional manner. The exhaust gases discharged therefrom, however, are oxygen-rich and relatively cool, as compared to those exhausted from conventional engines. The latter characteristics results because combustion in the primary combustion chamber is completed at a crank angle of between 5 and 15 after top center, as compared to 25 after top center for conventional spark ignition. Thus, a larger effective expansion ratio is provided and thermal efficiency of the engine is increased. It is here noted that during the exhaust stroke the value 100 is closed and that, due to the relatively unrestricted area of the orifice 52b provided by the mouthpiece 72b, gas from the primary chamber may readily flow into the secondary chamber.

Although the present invention is concerned primarily with the provision of the aforementioned controlled flow charcteristics between the secondary and primary chambers of the ignition device, it has also been found that ideal operation of the ignition device occurs when the volume of the secondary chamber therein is equal to between .03 and 0.5 that of the primary chamber and, preferably, .04 that of the primary chamber. Thus, it should be appreciated that the relative proportions of the components of the ignition device and the overall system will vary, depending upon the physical characterics of the engine upon which they are employed.

In conclusion, it is noted that through the employement of a breather conduit, such as the conduit 42, the oxygenrich exhaust dischargedfrom an engine employing the present invention may be utilized to burn hydrocarbon fumes from the crank case of the engine. Furthermore, the relatively low temperature of the exhaust gas discharged from engines employing the present invention results in the creation of less nitrogen-dioxide in the exhaust product than occurs withengines employing conventional ignition systems.

From the foregoing description, it is believed apparent that the present invention enables the attainment of the objects initially set forth herein. It is to be understood, however, that the invention is not intended to be limited to the details of the exemplary embodiments herein illustrated and described.

What is claimed is:

1. A device to effect the ignition of an air-fuel mixture within the primary combustion chamber of an internal combustion engine provided with a spark ignition system, said device comprising:

(a) a housing having:

(1) a secondary combustion chamber therein adapted to confine a spark ignitable air-fuel mixture;

(2) an orifice extending therethrough into communication with said secondary chamber; and

(3) securing means adapted to efiect the attachment thereof to said engine so as to establish sealed fluid communication between said primary and secondary chambers through said orifice;

(b) conduit means communicating with said secondary chamber, said means being adapted to be connected in fluid communication with a supply of an air-fuel mixture to effect the introduction thereof into said chamber;

(c) valve means operatively associated with said conduit means to, upon attachment of said housing to said supply, selectively open said conduit means to fluid flow during the intake portion of the cycle of said primary chamber and close said conduit means during the remaining portion of the cycle of said primary chamber;

(d) component means adapted to cooperate with the spark ignition system of said engine to effect the spark ignition of an air-fuel mixture contained in said secondary chamber; and,

(e) a Borda mouthpiece for said orifice provided interiorly of said housing, said mouthpice defining a portion of said orifice and openings into said secondary chamber to define an imperforate lip extending thereinto; and,

(f) a nozzle of substantially truncated conical shape extending from said mouthpiece in diverging relationship relative thereto and through said housing, said nozzle defining the remaining portion of said orifice.

2. A device according to claim 1, wherein:

(a) said securing means comprises a threaded section on said housing adapted to be received in a spark plug opening in said primary chamber forming part of the ignition system of said engine;

(b) said orifice extends longitudinally through said threaded section; and,

(c) said component means comprises a threaded spark plug opening extending through said housing and into communication with said secondary chamber, said opening being adapted to received a spark plug forming part of the ignition system of said engine.

3. A device according to claim 1, wherein:

(a) said securing means comprises a threaded section on said housing adapted to be received in a spark plug opening in said primary chamber forming part of the ignition system of said engine;

(b) said orifice extends longitudinally through said threaded section;

(c) said component means comprises:

(1) a first electrode mounted on said housing so as to be grounded to said engine upon receipt of said threaded section in said spark plug open- (2) a second electrode mounted on said housing in electrically insulated relationship to said first electrode, said second electrode being adapted to be electrically connected to a spark plug wire forming part of the ignition system of said engine and defining, with said first electrode, a spark gap within said secondary chamber;

(d) said conduit means comprises a tubular passage extending through said second electrode; and,

(c) said valve means is disposed within said tubular passage.

4. In an Otto cycle internal combustion engine comprising at least one primary combustion chamber and a spark ignition system therefor, a smog control system comprising:

(a) a housing having:

(1) a secondary combustion chamber therein adapted to confine a spark ignitable air-fuel mixture;

(2) an orifice extending therethrough into communication with said secondary chamber; and,

(3) means effecting the attachment thereof to said engine so as to establish sealed fluid communication between said primary and secondary chambers through said orifice;

(b) conduit means communicating with said secondary chamber through which an air-fuel mixture may be supplied thereto;

(c) primary carburetion means connected in fluid communication with said primary combustion chamber to supply an air-fuel mixture thereto having a ratio of from 16:1 to 20:1;

(d) secondary carburetion means connection in fluid communication with said conduit means to supply an air-fuel mixture to said secondary combustion chamber having a ratio of from 4:1 to 6:1;

(e) valve means operatively associated with said conduit means to selectively open said conduit means to fluid flow during the intake portion of the cycle of said primary chamber and close said conduit means means during the remaining portion of the cycle of said primary chamber;

(f) ignition means operatively associated with the spark ignition system of said engine to effect the spark ignition of an air-fuel mixture contained in said secondary chamber; and,

(g) a Borda mouthpiece for said orifice provided interiorly of said housing, said mouthpiece defining a portion of said orifice and opening into said secondary chamber to define an imperforate lip extending thereinto; and,

(h) a nozzle of substantially truncated conical shape extending from said mouthpiece in diverging relationship relative thereto and through said housing, said nozzle defining the remaining portion of said orifice.

5. Inan Otto cycle engine according to claim 4, further compnsmg:

(a) a crank case having a breather outlet; and,

(b) an exhaust conduit to receive gases exhausted from said primary chamber,

said smog control system further comprising:

(1) a breather conduit connecting said breather outlet in fluid communication with said exhaust conduit at a point wherein, during operation of said engine, the exhaust gases therein are at a temperature exceeding the ignition temperature of hydrocarbon fumes in said crank case; and,

(2) check valve means interposed in said breather conduit to prevent backflow therethrough from the exhaust conduit to the crank case.

6. In an Otto cycle engine according to claim 4, said smog control system wherein said primary and secondary carburetion means are each selectively controllable to vary the volume of air-fuel mixture supplied therethrough and further comprising means to eifect the control of said secondary carburetion means in substantially direct proportion to the control of said primary carburetion means.

7. In an Otto cycle engine according to claim 4, said smog control system wherein the volume of said secondary chamber is less than .05 that of said primary chamber.

8. In an internal combustion engine:

(a) a cylinder having a combustion chamber;

(b) a cylinder head having a precombustion chamber;

and,

(c) an orifice defining a throat section establishing communication between said chambers, said orifice comprising:

(1) a Borda mouthpiece opening into the pre- 11 12 combustion chamber to define an imperforate 2,758,576 8/1956 Schlamann. =1ip extending thereinto; and, 3,066,661 12/1962 May. (2) a nozzle of diverging area extending from 3,066,662 12/1962 May et 31.

said mouthpiece in diverging relationship rela- 3,102,521 9/1963 Slemmons 123-32 iitxl gmtggeto and opening into said combustion 5 OTHER REFERENCES References Cited Rocket Propulsion Elements, Sutton, 2nd edition, John UNITED STATES PATENTS Wiley & Sons Inc., New York, pp. 71-73 and 189.

2,121920 6/1938 Mallory 123 143 LAURENCE M. GOODRIDGE, Primary Examiner.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.6. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,406,667 October 22, 1968 Alvin W. Evans et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 32, "openings" should read opening Signed and sealed this 9th day of December 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

